Liquid–liquid phase diagrams of ternary systems as a function of temperature: isooctane + aromatic + methanol with and without water

We have determined experimentally the liquid–liquid equilibrium of the ternary systems isooctane+aromatic hydrocarbon (o-xylene, +m-xylene, and +ethylbenzene) +methanol, at 298.15 K, using gas chromatography together with a calibration and the internal standard method. Furthermore, we have studied the effect of temperature on the miscibility of methanol with hydrocarbons through the measurement of the phase diagram of the system isooctane+o-xylene+methanol, at 283.15 and 308.15 K. The experimental tie-line data obtained define the binodal curve for each one of the studied systems. Since, the presence of water in hydrocarbon mixtures greatly modifies the solubility of methanol, we have also obtained experimental “isowater” tolerance curves for the system isooctane+methanol+o-xylene at 283.15, 298.15, and 308.15 K. The experimental tie-line data for the different ternary systems were correlated with the NRTL and UNIQUAC solution models and plait points were derived.